Write LMI constraint H2 problem

How I write the following LMI constraint: trace(CrPCr') < a^2. Where 'a' is a positive number.

Remember, I don't want solve this LMI with mincx, I want put this as a constraint.

For more information about that problem see: On the design of multivariable PID controllers via LMI approach. Zheng, F., Wang, Q.Guo, Lee, Tong H.

[Arianna Senesi]

Did you find a solution? Thanks